1. Field of the Invention
The present invention relates to a rolling bearing device that is used in supporting a high speed spindle employed in, for example, a machine tool spindle device.
2. Description of the Related Art
The guide system in the retailer employed in a rolling bearing device has been known in three types; an outer ring guide system, an inner ring guide system and a rolling element (ball or roller) guide system. In the machine tool spindle device, the rolling bearing device is largely employed with an inner ring used as a rotating member and, therefore, with the retainer of the inner ring guide system, a lubricant oil is difficult to be retained on a guide surface due to a centrifugal force. Accordingly, in terms of lubricity, the machine tool spindle device largely make use of rolling bearing devices employing the retainer of the outer ring guide system or the rolling element guide system. On the other hand, in the case of the rolling bearing device utilizing the retainer of the rolling element guide system, the retainer tends to considerably fluctuate during rotation. In this respect, since in the rolling bearing device utilizing the retainer of the outer ring guide system, the rotator fluctuation of the retainer can be suppressed by the outer ring, the use of the rolling bearing device utilizing the retainer of the outer ring guide system (such as disclosed in the Patent Document 1 listed below) as a bearing for the machine tool spindle device brings about such an advantage found in stability of movement of the retainer and also in securement of the lubricant oil on the guide surface particularly during a high speed rotation.
Also, as a rolling bearing device designed to cope with a high speed feature of the machine tool spindle device, the rolling bearing device (such as disclosed in, for example, the Non-Patent Document 1 listed below) has been suggested, in which an inner ring has an outer diametric surface provided with an inclined surface portion and a nozzle member having a nozzle for injecting an air-oil, which is a mixture of a conveyance air with a lubricant oil, is laid along the inclined surface portion with a gap intervening between it and the inclined surface portion to represent an environmentally friendly lubricating structure. In the case of this lubricating structure, the lubricant oil jetted from the nozzle can be guided along the outer diametric surface of the inner ring towards the inside of the bearing device and, therefore, as compared with the case with the standard air-oil supply such as the direct discharging of the air-oil from the gap between the retainer and the raceway towards the rolling elements, the silencing property is excellent and the amount of both of air and oil consumed can be advantageously minimized.
In addition, the Non-Patent Documents 2 and 3 listed below describe a high speed orientation of the rolling bearing device. In particular, the Non-Patent Document 2 discloses the rolling bearing device utilizing such a material as fine ceramics, particularly silicon nitride (Si3N4). For use in the machine tool spindle device, the Non-Patent Document 2 also discloses formation of the rolling elements or raceway rings with the use of silicon nitride. On the other hand, the Non-Patent Document 3 discloses the rolling bearing device for the machine tool spindle device, in which silicon nitride (Si3N4) is used as a material. For example, examples in which only the rolling elements, both of the rolling elements and the inner ring or both of the rolling elements and the inner and outer rings are made of a ceramic material are disclosed in FIG. 2 in the Non-Patent Document 3.    [Patent Document 1] JP Laid-open Patent Publication No. 2006-329233    [Non-Patent Document 1] NTN Brochure, “Precision Rolling Bearing Devices”, CAT. No. 2260/J, pp 53    [Non-Patent Document 2] Journal of Japan Society for Precision Engineering, Vol. 54, No. 7, 1988, pp 1240-1244    [Non-Patent Document 3] Koyo ENGINEERING JOURNAL No. 135, 1989, pp 62-71